I was wondering why auto-proposals gives you better results. So, I asked my client to post a job and accept auto-proposals on it.
I can clearly see 2 reasons.
1) My proposal shows on top
2) He receives it as soon as he posts the job.
So, conversation start there and then. Client doesn't have to log-off and you don't need to wait for conversation to start. Increasing job award chances and your selection.